U.S. Pat. No. 687,158 relates to a process for the extraction of glycomacropeptide or caseinoglycomacropeptide (“cGMP”) from a lactic raw material. cGMP is a phosphorylated and partially sialylated macropeptide which is formed by the action of a protease, for example rennet, on mammalian milk kappa-casein. cGMP represents about 20% by weight of the proteins in sweet whey obtained after separation of casein during cheese manufacture.
This process comprises the steps of removing cations from a lactic raw material for a sufficient amount of time to obtain a substantially deionised lactic raw material having a pH of about 1 to 4.5; contacting the substantially deionised lactic raw material with an anionic resin having a hydrophobic matrix for a sufficient amount of time and at a sufficient temperature to remove cGMP from the substantially deionised lactic raw material and to obtain a treated liquid material; separating the resin from the treated liquid material; and rinsing the resin to obtain the cGMP therefrom. The cGMP is actually removed in a range from 85 to 91% of the starting cGMP.
The treated liquid material that is obtained from sweet whey has an amino acid profile reduced in threonine and enriched in aromatic amino acids such as tryptophan. It is useful in an infant or dietetic product as a protein source or raw material, in a pharmaceutical composition in combination with antithrombotic, antidiarrheal or antibacterial agents, or in a food composition as an emulsifying, gelling of foaming agent.
However, its amino acid profile, in particular the tryptophan and threonine contents, makes the treated liquid not always suitable for hypoallergenic formulae, and the manufacturer has to mix it with at least one different source of proteins and/or to add selected amino acids.
Moreover, the duration of the treatment and the amount of resin and treated liquid are chosen as a function of the composition of the starting material and the quantity of cGMP to be removed. In practice, this is achieved through experiments in the field work but no clear theoretical rule has emerged so as to facilitate the processing of the treatment.
Therefore one object of the invention is to provide a process for treating a sweet whey material comprising cGMP, on the basis of a simple and efficient setting, or to at least provide a useful alternative.
Another related object of the invention is to provide a method producing a protein material from a sweet whey material containing cGMP, said protein material having targeted tryptophan and threonine contents by the use of said process, or to at least provide a useful alternative.